Messages in this thread Patch in this message | | | Date | Fri, 21 Feb 2014 12:10:31 -0800 | From | Kees Cook <> | Subject | [PATCH] kallsyms: fix absolute addresses for kASLR |
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From: Andy Honig <ahonig@google.com>
Currently symbols that are absolute addresses are incorrectly displayed in /proc/kallsyms if the kernel is loaded with kASLR.
The problem was that the scripts/kallsyms.c file which generates the array of symbol names and addresses uses an relocatable value for all symbols, even absolute symbols. This patch fixes that.
Several kallsyms output in different boot states for comparison:
$ egrep '_(stext|_per_cpu_(start|end))' /root/kallsyms.nokaslr 0000000000000000 D __per_cpu_start 0000000000014280 D __per_cpu_end ffffffff810001c8 T _stext $ egrep '_(stext|_per_cpu_(start|end))' /root/kallsyms.kaslr1 000000001f200000 D __per_cpu_start 000000001f214280 D __per_cpu_end ffffffffa02001c8 T _stext $ egrep '_(stext|_per_cpu_(start|end))' /root/kallsyms.kaslr2 000000000d400000 D __per_cpu_start 000000000d414280 D __per_cpu_end ffffffff8e4001c8 T _stext $ egrep '_(stext|_per_cpu_(start|end))' /root/kallsyms.kaslr-fixed 0000000000000000 D __per_cpu_start 0000000000014280 D __per_cpu_end ffffffffadc001c8 T _stext
Signed-off-by: Andy Honig <ahonig@google.com> Signed-off-by: Kees Cook <keescook@chromium.org> --- scripts/kallsyms.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c index 10085de886fe..276e84b8a8e5 100644 --- a/scripts/kallsyms.c +++ b/scripts/kallsyms.c @@ -330,8 +330,7 @@ static void write_src(void) printf("\tPTR\t_text + %#llx\n", table[i].addr - _text); else - printf("\tPTR\t_text - %#llx\n", - _text - table[i].addr); + printf("\tPTR\t%#llx\n", table[i].addr); } else { printf("\tPTR\t%#llx\n", table[i].addr); } -- 1.7.9.5
-- Kees Cook Chrome OS Security
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